Atomic Structure of GRK5 Reveals Distinct Structural Features Novel for G Protein-coupled Receptor Kinases
Atomic Structure of GRK5 Reveals Distinct Structural Features Novel for G Protein-coupled Receptor Kinases
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DOI：
10.1074/jbc.m115.647297
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发表时间：
2015-08-21
影响因子：
4.8
通讯作者：
Benovic, Jeffrey L.
中科院分区：
文献类型：
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作者：
Komolov, Konstantin E.;Bhardwaj, Anshul;Benovic, Jeffrey L.
G 蛋白偶联受体激酶 (GRK) 是蛋白激酶 A、G 和 C 家族 (AGC) 的成员，在介导 G 蛋白偶联受体磷酸化和脱敏中发挥核心作用。 GRK5 家族的一个成员与多种人类疾病有关，包括心力衰竭、高血压、癌症、糖尿病和阿尔茨海默病。为了深入了解 GRK5 功能的机制，我们以 1.8 埃的分辨率确定了全长人类 GRK5 的晶体结构。 GRK5 与 ATP 类似物 5'-腺苷酰β,γ-亚胺二磷酸或核苷桑吉瓦霉素形成复合物，结晶为单体。 AGC 激酶结构域的 C 末端尾部 (C-tail) 是一个高度保守的特征，分为以下三个片段：C 叶系链、活性位点系链 (AST) 和 N 叶系链 (NLT)。该结构域在 GRK5 中被完全解析，并揭示了与核苷酸和 N 叶的新相互作用。与其他 AGC 激酶类似，GRK5 AST 是核苷酸结合口袋的组成部分，这是其他 GRK 中未观察到的特征。 AST 还介导激酶 N 叶和 C 叶之间的接触，促进激酶结构域的闭合。 GRK5 NLT 很大程度上偏离了之前在其他 GRK 中观察到的位置。此外，尽管 NLT 中的自磷酸化位点距催化裂口 > 20 埃，但它们能够快速顺式自磷酸化，表明该区域具有高迁移率。总之，我们提供了处于部分闭合状态的 GRK5 快照，其中激酶结构域 C 尾的结构元件对齐，形成与核苷酸和 N 叶的新相互作用，这是以前在其他 GRK 中未观察到的。
G protein-coupled receptor kinases (GRKs) are members of the protein kinase A, G, and C families (AGC) and play a central role in mediating G protein-coupled receptor phosphorylation and desensitization. One member of the family, GRK5, has been implicated in several human pathologies, including heart failure, hypertension, cancer, diabetes, and Alzheimer disease. To gain mechanistic insight into GRK5 function, we determined a crystal structure of full-length human GRK5 at 1.8 angstrom resolution. GRK5 in complex with the ATP analog 5'-adenylyl beta,gamma-imidodiphosphate or the nucleoside sangivamycin crystallized as a monomer. The C-terminal tail (C-tail) of AGC kinase domains is a highly conserved feature that is divided into three segments as follows: the C-lobe tether, the active-site tether (AST), and the N-lobe tether (NLT). This domain is fully resolved in GRK5 and reveals novel interactions with the nucleotide and N-lobe. Similar to other AGC kinases, the GRK5 AST is an integral part of the nucleotide-binding pocket, a feature not observed in other GRKs. The AST also mediates contact between the kinase N- and C-lobes facilitating closure of the kinase domain. The GRK5 NLT is largely displaced from its previously observed position in other GRKs. Moreover, although the autophosphorylation sites in the NLT are > 20 angstrom away from the catalytic cleft, they are capable of rapid cis-autophosphorylation suggesting high mobility of this region. In summary, we provide a snapshot of GRK5 in a partially closed state, where structural elements of the kinase domain C-tail are aligned to form novel interactions to the nucleotide and N-lobe not previously observed in other GRKs.